All premature babies being treated in Northern Ireland's neonatal units are being tested for the pseudomonas bacterium.

The tests will be carried on those premature infants being treated in units where the bug was present, it was confirmed on Wednesday.

Three babies died in an outbreak at the Royal Jubilee Maternity hospital in Belfast and seven other infants have the infection, which causes lung, blood and urinary problems. Another baby died of a related infection in the Altnagelvin hospital in Derry last month.

Northern Ireland's public health agency confirmed on Wednesday that the number of cases of pseudomonas had not changed.

The health minister Edwin Poots revealed on Tuesday that taps in the unit at the Belfast hospital carried the infection.

He added that the pipe work and taps in the unit were being replaced, and there was no evidence that pseudomonas was in the water supply.

Poots was expected to be quizzed further over the outbreak at a meeting of the Northern Ireland assembly health committee later on Wednesday.

Expectant mothers who need neonatal care will be treated at other facilities in Northern Ireland, Britain or the Irish Republic.

Taps with ultraviolent lighting are to be installed which can kill bacteria and the unit will only be reopened once all remedial work is completed and tests show that it is safe.